抄録
The deployment of solar energy systems in Japan has sometimes raised environmental concerns due to installations in sensitive areas such as forests. In response, many municipalities have introduced regulations to restrict solar development in these zones. To expand solar energy systems and achieve decarbonization goals, identifying suitable areas such as low-conflict land is essential. However, previous studies assessing the technical potential have often overlooked both recent regulatory constraints and rooftop-specific spatial limitations. Here, we assess the technical potential of solar energy systems by constructing a geospatial database with detailed land-use classifications based on a policy review of 263 municipalities. Our analysis shows that incorporating regulatory constraints significantly reduces the land available for ground-mounted solar energy systems. In contrast, most rooftop potential is found in small buildings, where high installation costs remain a barrier. These findings suggest that shifting solar deployment from ground-based to rooftop systems is critical for sustainable expansion. Policymakers should set suitable targets and design support schemes for rooftop solar adoption, particularly for small-scale installations. This study provides a framework for integrating policy and spatial constraints into national renewable energy planning.
